From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The investigation of volt-drop in an experimental cutout unit compared to a standard model.
| Identifier | ExFiles\Box 168a\3\ img235 | |
| Date | 7th October 1915 | |
| -2- He/Wat.10/WA.{Mr Wallis}7.10.15. Cont'd.{John DeLooze - Company Secretary} From these results it is seen that, not only is the tractive force greatly increased, but the circuit is still not fully saturated at maximum excitation. With the shunt coil supplied at 12.0 volts, the force available for compressing the contacts is - Standard 2.75 ozs. Experimental 10 ozs. The reverse current of the experimental unit was found to be rather high, i.e. 2.2 amperes as compared with .5 ampere, approximately. (2) Investigation of volt-drop. After correctly adjusting the cutout by suitably altering the contact spring etc., the voltage drop across different portions of the unit were measured as follows :- (1) Across the contact points. (2) Across the armature and hinge. (3) Across the core and series coil. With 12.0 volts applied to the shunt coil, and 20.0 amperes in the series circuit :- Portion of cutout. Std. Volt Drop. Expl. Expl. with two flexibles removed. 1. .056 volt .034 volt .035 volt. 2. .020 " .030 " .030 " 3. .330 " .270 " .278 " The two flexibles removed were the one in parallel with the armature and the one in parallel with the core. The results indicate that these two flexibles are serving no useful purpose. The small increase in (2) on the experimental unit suggests that the flexible bridging the hinge, should be increased to the size of that on the standard. Apart from this, there is an appreciable reduction in voltage drop over the cutout with the new unit. | ||